Paleo-environmental change in Haukadalsvatn core HAK03-1B over the last 2 ka compared with Northern Hemisphere temperature reconstructions. A. The ratio of biogenic silica to total organic carbon (BSi:TOC). B. TOC. C. BSi. Curves in A, B, and C are 4 point running means. D. Mann and Jones (2003) Northern Hemisphere temperature anomaly (40 year smoothed version of the decadally resolved reconstructed temperature series). E. Moberg et al. (2005) reconstructed Northern Hemisphere temperatures calculated by combining low-resolution proxies with tree-ring data, using a wavelet transform technique to achieve timescale-dependent processing of the data. Dotted, vertical line through all graphs shows the Settlement tephra layer. MWP = Medieval Warm Period.